title: Vitamin D deficiency is associated with pulmonary exacerbations in children with cystic fibrosis.
abstract: BACKGROUND
  Recent literature suggests vitamin D has an effect on lung function and on the lung's ability to fight infection, both important in the cystic fibrosis (CF) population as predictors of morbidity and mortality.
  
  
  OBJECTIVE
  Our study assessed associations between vitamin D and % predicted lung function, pulmonary exacerbations, and first Pseudomonas aeruginosa infection in children with CF. We hypothesized that children with CF who have 25-hydroxy vitamin D (25-OHD) levels less than 30 μg/L would have lower % predicted lung function and more pulmonary exacerbations than those with 25-OHD greater than or equal to 30 μg/L.
  
  
  METHODS
  This retrospective longitudinal study of 130 children aged 6 to 18 years between 2000 and 2012 examined 25-OHD levels classed in three vitamin D groups: sufficient (≥30 μg/L), insufficient (20-29 μg/L), and deficient (<20 μg/L). Longitudinal models followed individuals' changing vitamin D groups over time to compare numbers of pulmonary exacerbations (defined by hospitalization), incidence of first P. aeruginosa infection, and % predicted lung function. Cross-sectional comparisons between vitamin D groups were performed at ages 8, 12, and 16 years.
  
  
  RESULTS
  The prevalence of vitamin D deficiency and insufficiency increased slowly through adolescence. The rate of exacerbations for the deficient vitamin D group, aged 15 to 18 years, was 13.1 per 10 patient-years, significantly higher than 4.3 per 10 patient-years for the insufficient and sufficient vitamin D groups (P < 0.05), which were not significantly different There were no differences between vitamin D groups in pulmonary function or incidence of first P. aeruginosa infection, which was about 2 per 10 patient-years.
  
  
  CONCLUSIONS
  Higher 25-OHD levels in children with CF were associated with lower rates of pulmonary exacerbations and, in adolescents, higher FEV1.
authors.affiliation: 1 Department of Pediatrics, Marshfield Clinic, Marshfield, Wisconsin; and.
authors.forename: Laura A
authors.initials: LA
authors.lastname: McCauley
authors.forename: William
authors.initials: W
authors.lastname: Thomas
authors.forename: Theresa A
authors.initials: TA
authors.lastname: Laguna
authors.forename: Warren E
authors.initials: WE
authors.lastname: Regelmann
authors.forename: Antoinette
authors.initials: A
authors.lastname: Moran
authors.forename: Lynda E
authors.initials: LE
authors.lastname: Polgreen
mesh_terms: D000293:Adolescent; D002648:Child; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D003550:Cystic Fibrosis / Q000453:epidemiology* / Q000503:physiopathology; D018450:Disease Progression; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D011552:Pseudomonas Infections / Q000453:epidemiology* / Q000503:physiopathology; D011550:Pseudomonas aeruginosa; D012129:Respiratory Function Tests; D012141:Respiratory Tract Infections / Q000453:epidemiology* / Q000503:physiopathology; D012189:Retrospective Studies; D012307:Risk Factors; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000453:epidemiology*
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D